Artificial knee joint



Patente'd Mar. 1, 1927.

UNITEDSTATESv PATENT ,ori-"ica,

HEINRICH nnrrivr, or NURL'MBERG, GERMANY.

ARTIFICIAL KNEE JOINT.

Application led September 29, 1924, Serial No. 740,648, and in Germany February 16, 1924.

The artificial knee oints which have hitherto been produced in using hinge-joints present theinconvenience that they wear off rapidly as the supporting surface of the joint axle is only small, and that there is no stability when the knee is bent. It has been proposed to use, for avoiding these inconveniences, sliding joints in which the ends in contact of the upper thigh and of the shank partly roll and partly slide the one on the other in accordance with the natural process when bending the knees. In this manner a larger bearing surface is obtained, but grave inconveniences are created as the joint is very sensitive and expensive as in order to produce the desired movement of the joint elements a complicated system of hingedly connected bars is required. A further inconvenience is that the joint can be adjusted not at all or only with great diiiiculties. At the bending of the knee the upper element of the joint moves forward and the direction of pressure of the upperthigh advances in front of the toe sooner than is the case in the hinge-joints so that the leg gives way.

This invention relates to a knee-joint with hinge-joint in which the inconveniences of the commonly used hinge-joint and those of the sliding joints are avoided.

The improved knee joint is shown by way of example on the accompanying` drawing, in which Figs. 1 and 2 show the knee joint in side elevation and front elevation respectively,

the upper thigh and the shank being in section.

Figs. 3 and 4 shown a joint in vertical section viewed from the side and from the front respectively. n

In the upper thigh 1 the joint element 2 and in the shank 3 the joint element 4 are inserted. The upper' element 2 has a lower curved surface 7 having a lnino' 2() of vulcanized fibre or the like. The lower element 4 which has preferably a lining 21 of sheet iron has in its upper surface a cavity which is greater than required for the curvature of the lower end of the upper element 2. The upper element 2 touches therefore the lower element at two points 5 and 6 (Fig. 3) situated at either side of the vertical central lever 9, 10is mounted, the arms of these levers being downwardly directed so that their ends project overl the front and rear faces of the lower element 4. The ends of one fork-shaped lever are connected with the ends of the other fork-shaped lever by means of cross bolts 11, l2. On these crossv bolts downwardly projecting bolts 13, 14 are fixed which traverse lateral projections 15, 16 of the lower element y4, nuts 17 18 being screwed on the lower ends of said screwy bolts so that they bear against the lower surfaces of said lateral projections. Apertures 22, 23 in the wall of the shank make these nuts accessible from outside. By means of the nuts the levers 9, l0 can be pulled downward so that the upper element 2 is pressed on the lower element 4 through the intermediary of the cross bolt 8.

Any wear of the joint can be easily coinpensated by tightening the nuts.v

The two elements 2 and 4 of the joint are pressed the one on the other by the action of the weight of the body so that the upper element 1s prevented from rotating with regard to the lowerelement beyond the desired degree eveny when the knee is being bent. The cross bolt 8 serves merely as pivot bolt for the upper joint element but not, as usually in hinge-joints, for intercepting the supporting pressure.

The improved joint permits of loading a bent knee as much as necessary so long as the leg is supported by the foot. When this joint is used the raising of the shoulders is avoided, which always happens when the artificial leg is not capableto support any load, the walking becomes more natural andthe physical strength is not wasted and the invalid is prevented from tumbling. y

I claim .An artificial knee joint comprising in combination an upper element having a curved lower surface, a joint bolt traversing this lower end of said upper element, a lower element having in its upper end a cavity in which said curved lower end of said upper element bears at a front and rear edge, two

tcal bore, screw bolts on said cross bolts and traversing the vertical bores of said pro`- ject/ions, and nuts screwed on the lower ends of Said screw bolts. 10

VIn testimony whereof I aix my signature.

HEINRICH REHM 

